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  • 11
    Publication Date: 2020-06-10
    Description: Source localization is one of the major research contents in the localization research of wireless sensor networks, which has attracted considerable attention for a long period. In recent years, the wireless binary sensor network (WBSN) has been widely used for source localization due to its high energy efficiency. A novel method which is based on WBSN for multiple source localization is presented in this paper. Firstly, the Neyman-Pearson criterion-based sensing model which takes into account the false alarms is utilized to identify the alarmed nodes. Secondly, the mean shift and hierarchical clustering method are performed on the alarmed nodes to obtain the cluster centers as the initial locations of signal sources. Finally, some voting matrices which can improve the localization accuracy are constructed to decide the location of each acoustic source. The simulation results demonstrate that the proposed method can provide a desirable performance superior to some traditional methods in accuracy and efficiency.
    Print ISSN: 1687-725X
    Electronic ISSN: 1687-7268
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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  • 12
    Publication Date: 2020-06-04
    Description: The Gaussian mixture filter can solve the non-Gaussian problem of target tracking in complex environment by the multimode approximation method, but the weights of the Gaussian component of the conventional Gaussian mixture filter are only updated with the arrival of the measurement value in the measurement update stage. When the nonlinear degree of the system is high or the measurement value is missing, the weight of the Gauss component remains unchanged, and the probability density function of the system state cannot be accurately approximated. To solve this problem, this paper proposes an algorithm to update adaptive weights for the Gaussian components of a Gaussian mixture cubature Kalman filter (CKF) in the time update stage. The proposed method approximates the non-Gaussian noise by splitting the system state, process noise, and observation noise into several Gaussian components and updates the weight of the Gaussian components in the time update stage. The method contributes to obtaining a better approximation of the posterior probability density function, which is constrained by the substantial uncertainty associated with the measurements or ambiguity in the model. The estimation accuracy of the proposed algorithm was analyzed using a Taylor expansion. A series of extensive trials was performed to assess the estimation precision corresponding to various algorithms. The results based on the data pertaining to the lake trial of an unmanned underwater vehicle (UUV) demonstrated the superiority of the proposed algorithm in terms of its better accuracy and stability compared to those of conventional tracking algorithms, along with the associated reasonable computational time that could satisfy real-time tracking requirements.
    Print ISSN: 1076-2787
    Electronic ISSN: 1099-0526
    Topics: Computer Science , Mathematics
    Published by Hindawi
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  • 13
    Publication Date: 2020-06-27
    Description: A computational method is developed to study the dynamics of lightweight deployable structures during the motion process without regard to damping. Theory and implementation strategy of the developed method are given in this study. As a case study, the motion process of a bar-joint structure and a ring array scissor-type structure was simulated under external dynamic loading. In order to verify the effectiveness of the method, the simulation results are compared with the results predicted by the authenticated multibody system dynamics and simulation program. It shows that the method is effective to dynamic analysis of deployable structures no matter the structures are rigid or elastic. Displacement, velocity, and acceleration for the entire deployable structures during the motion process can be computed, as well as strain if the deployable structure is elastic.
    Print ISSN: 1070-9622
    Electronic ISSN: 1875-9203
    Topics: Mathematics
    Published by Hindawi
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  • 14
    Publication Date: 2020-06-17
    Description: Considering the complexity and uncertainty of decision-making in the operating environment of an unmanned underwater vehicle (UUV), this study proposes an autonomous decision-making method based on the dynamic influence diagram (DID) and expected utility theory. First, a threat assessment model is established for situation awareness of the UUV. Accordingly, a DID model is developed for autonomous decision-making of the UUV. Then, based on the threat assessment results for the UUV, the utility of each decision-making plan in the decision-making nodes is inferred and predicted. Subsequently, the principle of maximum expected utility is used to select an optimal autonomous decision-making plan. Finally, the effectiveness of the DID method is verified by simulation. Compared with the traditional expert systems, the DID system shows great adaptability and exhibits better solutions of dynamic decision problems under uncertainty.
    Print ISSN: 1076-2787
    Electronic ISSN: 1099-0526
    Topics: Computer Science , Mathematics
    Published by Hindawi
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  • 15
    Publication Date: 2020-09-26
    Description: Carbon policies and consumer environmental consciousness are effective motivators that drive enterprises to adopt sustainability technology. To provide enterprises insights into sustainable investment and inventory-transportation decision-making and governments insights into policy-making, this study investigates integrated inventory-transportation scheduling considering consumer environmental consciousness and sustainability technology under carbon cap, tax, and cap-and-trade policies. We first examined sustainability that extends the economic order quantity (EOQ) models, simultaneously taking into account the comprehensive emission model, consumer environmental consciousness, and carbon policies. We then optimized the sustainability level and EOQ using the simulation method. Furthermore, we performed a regression analysis on the carbon policy effects on sustainability level, profit, and emission. Moreover, using the regression models, we estimated and discussed the optimal policy parameters from the perspective of social welfare maximization. The results indicate that the carbon cap-and-trade policy is superior to carbon cap and tax policies. Under carbon cap and tax policies, the tougher the carbon policy, the higher the sustainability level and the lower the profit and carbon emission. Meanwhile, under the carbon cap-and-trade policy, the carbon trading price is the decisive factor that affects the sustainability level, enterprises’ profit, and carbon emission; the carbon cap has a positive regulatory effect on profit.
    Print ISSN: 1026-0226
    Electronic ISSN: 1607-887X
    Topics: Mathematics
    Published by Hindawi
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  • 16
    Publication Date: 2020-08-17
    Description: In this paper, lightweight carbon/carbon fiber composite thermal field insulation materials were fabricated by the process method of long carbon fiber airflow netting-needle punching forming felt-resin impregnation-molding curing-high-temperature carbonization and graphitization. The microscopic morphology, conductivity, bending strength, and thermal conductivity of carbon/carbon fiber composites were measured by using the scanning electron microscope (SEM), four probes, electronic universal testing machine, and thermal analyzer. The results show that the long carbon fiber in the carbon/carbon fiber composite forms a three-dimensional structure of X-Y-Z with a density of 0.16 ± 0.02 g/cm3, which makes the composite material have excellent thermal insulation performance at high temperature, and the conductivity is 1452.4 S/m (plane direction) and 182.8 S/m (perpendicular to the plane direction), the compressive strength is 0.2 MPa (plane direction) and 1.31 MPa (perpendicular to the plane direction), the bending strength is 0.24 MPa (plane direction) and 1.1 MPa (perpendicular to the plane direction), and the thermal conductivity is 0.076 W/(mK) (25°C) and 0.17 W/(mK) (1200°C), respectively. The above process methods and test results will provide the application of the carbon/carbon fiber composite in the solar polysilicon furnace, single crystal silicon furnace, semiconductor furnace, sapphire furnace, fiber drawing furnace, and high-end metallurgical heat treatment furnaces, as well as applications in other high-temperature insulation environments, and also provide some suggestions in these insulation applications.
    Print ISSN: 2090-9063
    Electronic ISSN: 2090-9071
    Topics: Chemistry and Pharmacology
    Published by Hindawi
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  • 17
    Publication Date: 2015-01-01
    Description: The radar-enhanced GSI (version 3.1) system and the WRF-ARW (version 3.4.1) model were modified to assimilate radar/lightning-proxy reflectivity. First, cloud-to-ground lightning data were converted to reflectivity using a simple assumed relationship between flash density and reflectivity. Next, the reflectivity was used in the cloud analysis of GSI to adjust the cloud/hydrometeors and moisture. Additionally, the radar/lightning-proxy reflectivity was simultaneously converted to a 3D temperature tendency. Finally, the model-calculated temperature tendencies from the explicit microphysics scheme, as well as cumulus parameterization at 3D grid points at which the radar temperature tendency is available, were updated in a forward full-physics step of diabatic digital filter initialization in the WRF-ARW. The WRF-GSI system was tested using a mesoscale convective system that occurred on June 5, 2009, and by assimilating Doppler radar and lightning data, respectively. The forecasted reflectivity with assimilation corresponded more closely to the observed reflectivity than that of the parallel experiment without assimilation, particularly during the first 6 h. After assimilation, the short-range precipitation prediction improved, although the precipitation intensity was stronger than the observed one. In addition, the improvements obtained by assimilating lightning data were worse than those from assimilating radar reflectivity over the first 3 h but improved thereafter.
    Print ISSN: 1687-9309
    Electronic ISSN: 1687-9317
    Topics: Geosciences , Physics
    Published by Hindawi
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  • 18
    Publication Date: 2015-01-01
    Description: Objective. To investigate the impact of seven-valent pneumococcal conjugate vaccine on tube insertions in a partial immunized pediatric population.Study Design. Retrospective ecological study.Methods. This study used Taiwan National Health Insurance Research Database for the period 2000–2009. Every child under 17 years old who received tubes during this 10-year period was identified and analyzed. The tube insertion rates in different age groups and the risk to receive tubes in different birth cohorts before and after the release of the vaccine in 2005 were compared.Results. The tube insertion rates for children under 17 years of age ranged from 21.6 to 31.9 for 100,000 persons/year. The tube insertion rate of children under 2 years old decreased significantly after 2005 in period effect analysis (β= −0.074,P〈 0.05, and the negativeβvalue means a downward trend) and increased in children 2 to 9 years old throughout the study period (positiveβvalues which mean upward trends,P〈 0.05). The rate of tube insertion was lower in 2004-2005 and 2006-2007 birth cohorts than that of 2002-2003 birth cohort (RR = 0.90 and 0.21, 95% CI 0.83–0.97 and 0.19–0.23, resp.).Conclusion. The seven-valent pneumococcal conjugate vaccine may reduce the risk of tube insertion for children of later birth cohorts. The vaccine may have the protective effect on tube insertions in a partial immunized pediatric population.
    Print ISSN: 2356-6140
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
    Published by Hindawi
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  • 19
    Publication Date: 2013-01-01
    Description: Word sense disambiguation (WSD) is a fundamental problem in nature language processing, the objective of which is to identify the most proper sense for an ambiguous word in a given context. Although WSD has been researched over the years, the performance of existing algorithms in terms of accuracy and recall is still unsatisfactory. In this paper, we propose a novel approach to word sense disambiguation based on topical and semantic association. For a given document, supposing that its topic category is accurately discriminated, the correct sense of the ambiguous term is identified through the corresponding topic and semantic contexts. We firstly extract topic discriminative terms from document and construct topical graph based on topic span intervals to implement topic identification. We then exploit syntactic features, topic span features, and semantic features to disambiguate nouns and verbs in the context of ambiguous word. Finally, we conduct experiments on the standard data set SemCor to evaluate the performance of the proposed method, and the results indicate that our approach achieves relatively better performance than existing approaches.
    Print ISSN: 2356-6140
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
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  • 20
    Publication Date: 2015-01-01
    Description: The discontinuous deformation analysis (DDA) has been extensively applied in geotechnical engineering owing to its salient merits in the modeling of discontinuities. However, this method assumes a constant stress field within every block and hence cannot provide reliable estimation for block deformations and stresses. This paper proposes a novel scheme to improve the accuracy of the DDA. In our method, advanced subdivision is introduced to represent a block as an assembly of triangular or quadrilateral elements, in which overlapped element edges are separated from each other and are glued together by bonding springs. The accuracy and the effectiveness of the proposed method are illustrated by three numerical experiments for both continuous and discontinuous problems.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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